Tropical Rainforest Plants: the Bottom Line

In recent years, increasing attention has been given to the value of tropical rainforests as a source of non-timber forest products (NTFPs). Although the commercial value of many of these products has been calculated, the value of tropical pharmaceuticals has not been adequately assessed.

Tropical forests are recognized as a vast source of unknown chemicals with potential medicinal uses. Traditional medicinal plants are also the basis for much of the primary health care in tropical nations, such as Belize, where up to 75% of primary health care is provided by traditional practitioners using these plants. This paper quantifies the value of forests for their pharmaceutical products using data from Belize, Central America.

Currently, forest pharmaceuticals are harvested in two general ways, destructive and nondestructive. Frequent harvesting often leaves medicinal plants damaged and is thus unsustainable. Although these methods can degenerate a small site, it has been hypothesized that the process could be sustainable if applied to a larger area with longer rotations. This form of sustainable harvesting is evaluated in this paper. Other methods of more continuous harvesting are being examined in Belize and will eventually be evaluated.

To quantify the value of managing forests as a source of traditional medicines, inventory of plant materials was taken from two sites. Both sites were secondary hardwood forests representative of the region, in the Cayo District of Belize. Site 1 is 0.28 ha, and site 2 is 0.25 ha. Site 1 is about 30 years old, located in a valley at 200m elevation. Site 2 is about 50 years old, located on a ridge in the foothills of the Mayan mountains at 350m elevation.

Marketable medicinal plant materials were collected from both site. Site 1 yielded 86.4 kg dry weight of material, and site 2 yielded 358.4 kg. On a per hectare bases, the sites yielded 308.6 and 1433.6 kg of dry weight of medicines respectively.

The current local market value of the unprocessed plant material, which farmers sell to local healers and pharmacists, is US$2.80/kg. At this rate the gross revenue of the two sites would be $864 and $4,014 respectively. The labor costs for harvesting the materials must also be considered. Collection time for site 1 was seven person-days, 20 person-days on site 2. On a per hectare basis this projects to 25 person-days on site 1, and 80 person-days on site 2. With a local wage of $12/day, total harvest costs of the two locations were $300 and $960, respectively. Subtracting these costs from the gross revenue, the net revenue per hectare for sites 1 and 2 is $564 and $3,054 respectively.

Information was insufficient to determine optimal rotation time for harvesting medicinal plant material. Instead, the current age of the sites was used as a rotation length. Given a 30 year rotation in site 1, the present value of medicinal plants in that site was calculated at $726/ha. With a 50 year rotation, site 2 yields a present value of $3,327/ha.

These estimates compare favorably with other land uses in the region, such as estimates of the present value of:

intensive agriculture in the Brazilian rainforest, $339/ha.

milpa (corn, beans and squash) in the Guatemalan rainforest, $228/ha.

anticipated yield of pine plantations proposed for the tropics, $3,184/ha.

Other commercial plants exist in the trial sites that could be harvested and increase the total value. These plants include allspice (Pimenta dioica), copal (Protium copal), and chicle (Manilkara zapota), among others. Thus, the data suggest that protection of at least some areas of rainforest as extractive reserves seems to be economically justified. According to this analysis, which is based on current market data, a periodic harvest strategy is a realistic and sustainable method of using the forest.

This analysis is based on current market data. The dollar resulting value is subject to change depending on local market forces. The authors of this paper predict that, due to the harvesting of NTFPs, the value of tropical forests for the harvest of NTFPs will increase relative to other land uses over time as the forests become increasingly scarce.

Systems for sustainable collection of plant medicines and other NTFPs need to be documented and developed for use on a much broader scale. The present value of medicinal plants combined with that of other NTFPs provides a compelling and quantifiable argument for the conservation and careful management of tropical and subtropical forests.